# HG changeset patch
# User Matti Hamalainen <ccr@tnsp.org>
# Date 1530021327 -10800
# Node ID 2977baab68db689afc31a99be79394ef1bf95d63
# Parent  571109a14967e2cc9c3a50552d7c9396382e872c
Fix certain corner case in IFF ByteRun1 encoder.

diff -r 571109a14967 -r 2977baab68db tools/libgfx.c
--- a/tools/libgfx.c	Tue Jun 26 16:49:03 2018 +0300
+++ b/tools/libgfx.c	Tue Jun 26 16:55:27 2018 +0300
@@ -1977,7 +1977,7 @@
         if (l_count > *r_count || flush)
         {
             size_t count = l_count - *r_count;
-            Sint8 tmp = count - 1;
+            Uint8 tmp = count - 1;
 
             if (!dmf_write_byte(fp, tmp) ||
                 !dmf_write_str(fp, buf + *l_offs, count))
@@ -1987,14 +1987,16 @@
     }
     else
     {
-        unsigned int count = *r_count;
-        Sint8 tmp = -(count - 1);
+        if (*r_count > 0)
+        {
+            unsigned int count = *r_count;
+            Uint8 tmp = ((Uint8) count - 2) ^ 0xff;
 
-        if (!dmf_write_byte(fp, tmp) ||
-            !dmf_write_byte(fp, data))
-            return FALSE;
-
-        *r_count = 0;
+            if (!dmf_write_byte(fp, tmp) ||
+                !dmf_write_byte(fp, data))
+                return FALSE;
+            *r_count = 0;
+        }
         *l_offs = offs;
     }